This invention relates to apparatus for monitoring the loading of a lift, such as the loading of the work platform of an aerial work platform lift, and the loading of a forklift; and more particularly for sensing the load on the work platform of the aerial work platform lift or the tines of the forklift.
As to the monitoring of the loading of the work platform of an aerial work platform lift, reference may be made to U.S. Pat. No. 5,913,379 of Paul E. Young and David P. Engvall issued Jun. 22, 1999 entitled Articulated Aerial Work Platform System for a disclosure of the type of aerial work platform lift in which the monitoring apparatus or xe2x80x9cload sensor mountingxe2x80x9d apparatus of this invention is incorporated, with the understanding that the apparatus of the invention may be incorporated generally in aerial work platform lifts other than that shown in said U.S. Pat. No. 5,913,379, which is incorporated herein by reference. A problem which has existed with regard to such lifts has been that of detecting overloading (i.e. excessive weight) on the work platform of the lift, so that unsafe conditions due to overloading may be avoided. Excessive weight may be due to the weight of the workman (or workmen) standing on the work platform plus equipment and items being used, additive to the weight of the work platform itself. Attempts to solve this problem have been made; see, for example such prior U.S. Pat. No. as 3,952,879 issued Apr. 27, 1976 entitled Overload Control for Lifting Boom and U.S. Pat. No. 4,456,093 issued Jun. 26, 1984 entitled Control System for Aerial Work Platform Machine and Method of Controlling an Aerial Work Platform Machine. Other attempts have involved the use of multiple load sensors at various locations on the work platform. However, these systems are expensive and not particularly accurate. This invention is regarded as representing an improvement over such systems and what is disclosed in such prior U.S. Patents.
In addition to being applicable to monitoring the loading of the work platform of an aerial work platform lift, the invention is also applicable to the monitoring of the loading of other lifts, in particular a forklift, and especially a type of forklift referred to as a rough terrain forklift, such as used on construction sites to lift construction materials, for example. In such usage, the forklift may encounter the problem of a load being picked up on the tines of the forklift in a way as to result in a dangerous situation which, if not remedied, may cause the forklift to tip over. An adjunct of the invention involves detection of a potential tip-over condition.
Reference may also be made to the following U.S. Patents as of interest re the forklift application of the invention and re other potential applications thereof:
In general, a load lift of this invention comprises a lifter (e.g. the boom of an aerial work platform lift, the lifter of a forklift, or the like) and a linkage on the lifter carrying a load support (e.g. the aerial work platform, the tines of the forklift, or the like) for movement therewith to different elevations. The linkage comprises a first member carried by the lifter, a second member carrying the load support, said first and second members constituting side members of the linkage extending generally vertically, a third member constituting an upper member of the linkage pivotally connected to the first and second members, and a fourth member constituting a lower member of the linkage pivotally connected to the first and second members. An interconnection between said first and second members holds up said second member and load support. Instrumentation is provided for sensing the load on the load support.
This invention is also directed to a load sensor mounting per se (a unit for incorporation in a lift). The mounting generally comprises the linkage and instrumentation described above.
Other objects and features will be in part apparent and in part pointed out hereinafter.